The objective of this research is to investigate the mechanism(s) underlying rapid fluctuations of poly(A) polymerase observed under different physiological conditions. This will be achieved by determining (a) the actual number of enzyme molecules by a sensitive radioimmunoassay developed in our laboratory (Rose, K.M., Kumar, A. and Jacob, S.T., Nature 279, 260-262, 1979) and (b) the degree of phosphorylation of poly(A) polymerase which has been shown to result in enzyme activation (Rose, K.M. and Jacob, S.T., J. Biol. Chem. 254, 10256-10261, 1979) and augmentation in the rate of polyadenylation of mRNA (Rose, K.M. and Jacob, S.T., Biochemistry, in press). The protein kinase closely associated with poly(A) polymerase from the Morris hepatoma 3924A at early stages of purification will be extensively purified. This kinase utilized poly(A) polymerase efficiently as a substrate (Rose, K.M. and Jacob, S.T., J. Biol. Chem. 254, 10256-10261, 1979). The role of this protein kinase in the mRNA polyadenylation will be elucidated by investigating the substrate specificity, levels in the tumor relative to liver and other physico-chemical properties.